238 



The Ohio Journal of Science [Vol. XVII, No. 7, 



Callocystites sphaeroidalis, sp. nov. Plate XII, Fig. 5. 



Theca globular; only the cast of the exterior of a single specimen is 

 known, but this includes almost half of the specimen. That half of the 

 pectinirhomb which belongs to plate 15 is present and assists in orienting 

 the specimen. Plate 15 truncates plate 9, and plate 16 truncates plate 5; 

 moreover, there is evidence of the coinplete series of deltoids, 20 to 24, 

 forming the fourth row in Callocystites. A crack extends along the left 

 margin of plate 22, along the right margin of the ambulacrum on plate 

 16, across the left corner of plate 11, and then across plate 5 in a direction 

 parallel to its left margin, where in contact with plate 10. A slight 

 displacement has taken place along this crack, the left part of the 

 specimen being slightly depressed and pushed under the right part. 

 The ambulacrum crossing plate 16 divides dichotomously near the center 

 of this plate, one branch (d) following the line of contact between 

 plates 10 and 5, while the other branch (c) crosses the middle of the 

 latter plate. In addition to this there appears to be evidence of a third 

 branch (x) of the same ambulacrum, passing along the right hand 

 margin of plate 5, intruding slightly on plates 11 and 6. The bifurcation 

 for the third branch takes place near the left angle of plate 11. This 

 second bifurcation of the ambulacrum, although not observed hereto- 

 fore in Callocystites, is to be expected in view of the repeated bifurca- 

 tions in the later forms included under Sphaerocystites. That half of the 

 pectinirhomb which is present on plate 15 possesses about 15 dichopores; 

 it is semilunate in form, there is no evidence of a prominent border, and 

 it is not in contact with the margin of the plate. The surface of the 

 thecal plates is ornamented by small granules, about 4 in a length of 

 2 millimeters. 



Found in the Cedarville dolomite, in the eastern Mills 

 quarry, southwest of Springfield, Ohio. 



'6"+ 



Figure 3. Callocystites sphaeroidalis. Plate diagram on left side, and dia- 

 gram of ambulacra on right, both only partially preserved; the latter was drawn 

 from a cast of the exterior and, therefore, is inverted from right to left. H, hydro- 

 pore; p, pectinirhomb; a, b, branches of left posterior ray; c, d, branches of left 

 anterior ray; x, y, apparently supplementary branches; e, f, branches of the 

 anterior ray; the left anterior and anterior rays are indicated only by the grooves 

 left by the fallen-olT ambulacrals. 



